Method for the designing of tools

ABSTRACT

The invention concerns a method for the creation of addendums ( 4 ) of tools for sheet metal formed parts ( 2 ). In the case of this method, fill surfaces ( 7 ) for the smoothing of irregular zones of a component edge ( 3 ) are generated. Initial directions ( 31 ) of sectional profiles ( 10 ) are determined in such a manner, that sectional profiles ( 10 ) at a distance from one another are arranged along a component ( 3, 8 ) with utilization of these initial directions ( 31 ) and that an addendum ( 4 ) is creatable by the connection of these sectional profiles ( 10 ).

[0001] The invention presented here lies in the field of the designingof addendum zones of tools for the manufacture of formed sheet metalparts (deep-drawing/stretch-forming processes) and their optimization.The objective is solved by the invention as it is defined in the claims.

[0002] Formed sheet metal parts as a rule are manufactured bydeep-drawing. The semi-finished parts, the so-called sheet metal blanks(blank), for this purpose are placed in multi-part forming tools. Bymeans of presses, in which the forming tools are clamped, the parts areformed. The parts as a rule are manufactured out of a flat sheet metalblank in several forming steps (drawing, reshaping, setting, etc.),combined with trimming steps. In this process the edge areas, inparticular the addendums, represent problematic zones: In the designingof the tools for a forming step the concern is, i.a., to complement thecorrespondingly prepared component geometry, resp., in the case ofmulti-step processes, intermediate geometry (both hereinafter referredto as component geometry) in the edge zones by an addendum in such amanner, that from it a tool geometry is produced, with which thepredefined component geometry can be manufactured in such a way, that nofailure occurs (cracks and wrinkles) and that other qualityrequirements, for example, a limited reduction of the thickness, theachievement of a minimum stretching of the sheet metal, andmanufacturing technology restrictions are adhered to.

[0003] The dimensioning and adjustment of the addendums represents agreat problem field today. Not infrequently several months elapse, untila tool works satisfactorily. Frequently this is an iterative process,which is associated with a lot of rejected parts and a substantialconsumption of energy and other utilities. The producing of addendumstoday to a great extent takes place manually by means of computer-aideddesign systems (CAD) and takes a lot of time. In doing so, frequentlyhundreds of individual surfaces are created and edited by the designingof curves, supporting surfaces derived from them and their trimming.Already solely the establishment of an addendum for a large body partcan as a result easily take several weeks. This procedure in additioncalls for a great specialist knowledge in the fields of formingtechnology and CAD of the designer.

[0004] In the recent past, procedures have been developed andimplemented, which make possible the creation of addendums in a moreefficient manner. These are based on an addendum being described bymeans of flat sectional profiles. The known sectional profiles aredifferent to link resulting in bad interpolation data for addendumsurfaces. For most tools, in addition a limited number of such sectionalprofile types are sufficient. If one applies sufficient such flatsectional profiles radially outwards from the component edge, then fromit by an interpolation transverse to the sectional profiles the addendumsurface can be more or less automatically created. In doing so, theindication of a few sectional profiles is sufficient to be able to theninterpolate the sectional profiles from it. This method is notconvincing. By a variation of the sectional profiles the addendum can bevaried. With this procedure, the user in comparison to previously cansave time in the development and modification of the addendum. Theresulting addendum surfaces are still problematic due to insufficientresults from interpolation. These procedures are stand alone solutionsnot linked with other devices e.g. with simulation modules.

[0005] This procedure, however, has the following serious disadvantagesand problems. On the one hand, the smoothing of the edge of thecomponent represents a major problem. The edge of the componentgeometry, where the addendum is to be applied, is in most instances nota smooth curve, but frequently rather more has sharp-angledindentations, tongues, etc. If now the same sectional profile throughoutis applied to this edge, then these indentations, etc. continue into theaddendum, which can lead to an extremely irregular addendum surface. Inorder to prevent this, the user once again is compelled to manuallyintroduce many sectional profiles at the indentations and to adapt themin such a manner, that they lead to a fairly smooth addendum surface.Alternatively, it is attempted to first fill up and to equalize theindentations, tongues, etc., with the help of traditional CADfunctionality, so that a new, sufficiently large smooth component edgeis produced, from which then the sectional profiles are applied. Bothsolutions require a lot of time and lead to the result, that no usableaddendum can be produced fully automatically. The latter fact is adisadvantage in particular if one would like to automatically design,resp., optimize the addendum via an optimization loop in conjunctionwith a forming simulation code and a quality criterion. On the otherhand, the sectional profile direction is difficult to determineautomatically. The directions, in which the sectional profiles areapplied away from the component edge (resp., from the filled outcomponent edge), decisively determine the generated addendum surfaces.In applying the directions vertical to the edge of the componentprojected in the drawing direction, at concave points overlaps of thesectional profiles result, which makes the creation of the addendumsurface impossible.

[0006] It is the objective of the invention presented here todemonstrate a method how addendum surfaces for forming tools can beoptimized and created efficiently and easily avoiding the disadvantagesknown from prior art.

[0007] The invention divulged here is embedded in the process of tooldesigning (methods planning). The invention makes possible a significantreduction of the manufacturing effort, in that a new computer-basedmethodology is applied. Apart from the possibility of creating andvarying an addendum significantly more rapidly, in doing so it is alsopossible to create a best possible tool via an optimization loop inconjunction with a forming simulation code. The procedure described inthe invention presented here for the establishment of a parameterizedgeometry and process model, starting out from the component geometry,can be summarized in a simplified manner with the following steps:First, prepare the component geometry; second, determine the directionof drawing; third, create surface for the smoothing of irregular zonesof the edge of the component; fourth, generate binder surface; fifth,determine sectional profile directions; sixth, definition of sectionalprofiles at defined points; seventh, interpolation of intermediateprofiles using forming technology parameters for the creation of theaddendum surfaces; eighth, interactively adapt the characteristic lines,resp., automatically smooth them and correspondingly adapt addendumsurfaces; ninth, creation of the punch opening line as intersections ofthe sectional profiles with a binder surface and the smoothing, resp.,modification of it. When taking over the tool model into the simulation,the following steps for the definition of the process models follow:Extraction of the individual tool components from the generatedgeometries; specification of the blank outline or, in the case ofinverse simulation procedures, of the outline of the drawn-in sheetmetal; specification of the material, of the sheet metal thickness andof the direction of rolling; specification of the lubricationconditions; definition of the retaining devices (for example, draw bead,spacer, binder force); determination of the tool movements and ofpossible relieving steps during the forming. Iterative procedure betweenseveral of the above mentioned steps having an alternative sequence islikely if necessary. And single steps may also be omitted.

[0008] A tool for the forming of a blank in one stage as a rule consistsof three parts: A die, a binder and a punch. By means of the binder,which usually has a curved shape, the blank is pre-formed and fixed inan edge zone of the die. The actual deep drawing takes place, in thatthe blank is pressed into the die by means of the punch. The edge zonesare usually designated as complementary surfaces. These then are dividedinto binder surfaces located outside the punch zone and the addendumlocated inside the punch. These zones are decisive to fulfil the qualityrequirements. The addendum as a rule runs into the component and thebinder with a continuous tangent and is located within the action zoneof the die and of the punch. In the case of components with largecut-outs, such as the side wall frames of passenger vehicles, inaddition to the external addendum also several internal addendums can bepresent.

[0009] The invention presented here concerns a method, which makes itpossible, starting out from the geometry of a component, to as rapidlyas possible establish an in preference parameterized addendum and, if sorequired, a parameterized geometry and process model for a formingsimulation based on it. The objective is, as early as possible duringdevelopment, possibly already during the design of the component, tomake statements about the forming and manufacturing feasibility of acomponent with the help of forming simulations and taking into accountaddendums. With this, it is possible to make required corrections to thegeometry of the component at an early point in time. By means of asuitable parameterization it is possible, that the tool geometry (aswell as the addendum) and the process can be varied by means of few,scalar parameters. For a rapid assessment of different variants or alsowith a view to the automatic creation of an optimal addendum, if sorequired an optimization loop and/or a forming simulation code and/or aquality criterion are utilized in combination.

[0010] For the following description of the invention the assumption isdeparted from, that the forming tools move in a global z-co-ordinatedirection. This direction is designated as vertical; directions verticalto this axis (x,y-directions) are designated as horizontal. For purposesof simplification, it is assumed, that a component is free of undercuts,i.e., the projection in z-direction onto a horizontal plane shall be aone-to-one correspondence, with the exception of component surfaces inan exactly vertical direction.

[0011] The invention presented here contains, i.a., the idea ofsmoothing irregular zones of the component edges automatically ormanually, in preference towards the outside, i.e., away from the problemzones, and to automatically fill up the space produced with optimizedfill surfaces. These smoothed edges of the component are hereinafterreferred to as base lines. They can either be manually predefined or,for example, generated by geometrical smoothing algorithms, for example,by the virtual “unrolling” of a cylinder with a vertical axis along theedge of the component; this defines the x- and y-co-ordinate of the baseline; the z-co-ordinate is advantageously generated by the creation ofthe fill surfaces. Fill surfaces making sense in preference run into thecomponent geometry with a continuous tangent. Such surfaces are, forexample, generated by means of geometrical approximations taking intoconsideration the C1 edge condition (at the component edge), or, forexample by means of a finite elements shell solution with correspondingedge condition at the edge of the component (in this context refer toFIG. 2).

[0012] The horizontal directions of the sectional profiles as a ruledetermine how a geometrical detail of the component (feature), whichextends to the edge of the component, affects the addendum. It istherefore advantageous, that geometrical details in the componentgeometry and their branches in the addendum in essence have the samedirection. This presupposes, that a certain direction of the sectionalprofiles is a prerequisite (in this context refer to FIGS. 10, 11, 12).

[0013] In the invention presented here, the initial directions of thesectional profiles on the edge of a component are in preferencedetermined in such a manner, that they point in the direction of theminimum geometrical change in a defined, fictitious edge zone of thecomponent or in correlation with the flow-direction of the material.Alternative arrangements e.g. in concave areas are possible to avoidnegative overlapping. The fictitious edge zone of the component is herenotionally formed by a fictitious strip along the edge of the component(resp., the base line), lying in the inside of the component. This edgezone as a rule has a width, which, e.g., corresponds to approximately10-times the thickness of the sheet metal. How the direction of theminimum geometry change can be determined is illustrated in FIG. 5. Ifnecessary adjustments of the initial directions are possible, e.g. toavoid disadvantageous overlapping of sectional profiles in concaveareas.

[0014] In order to avoid the problem field associated with prior art ofan overlapping of sectional profiles, in particular in the zone ofconcave edge points of a component, the invention makes use of definedsectional profiles. These as a rule do not run in a plane, but in acurved surface. Alternative arrangements are possible e.g. as long as nointersection is occurring. Preferred examples of such surfaces arecylindrical or parabolic surfaces with a e.g. vertical alignment. Thesectional curves of these profiles with a horizontal plane are thereforecurved or straight curves. These curves serve as horizontal directrixesfor the sectional profile. The course of the directrixes is determinedby means of geometrical algorithms (polynomial approaches).Alternatively, it is also possible to proceed as follows: Departing fromthe edge of the component, the curves are applied as flectional beams,which are fixed to the edge of the component in the direction of aminimum geometry change and are connected transverse to one another withan elastic continuum or with springs. A corresponding model, forexample, is brought to the static equilibrium with the finite elementsmethod (FEM). (In this context refer to FIG. 4).

[0015] According to prior art, up until now the vertical course of thesectional profiles was predefined either through spline curves (forexample, B-splines or Bézier curves) or through geometrical basicelements such as line segments, curves, etc, which are put together in atangent-continuous course. While the first makes possible an easychanging of a sectional profile, it has, however, the disadvantage, thataccurate dimensions or the accurate geometry of a part of a curve, forexample, a draw bar height or a draw bar radius, it is very difficult toaccurately predefine. In the case of the second type of specification,while accurate dimensions can be determined, changes, however, arelaborious, because the tangent condition between the basic elementsalways has to be adhered to. In order to create addendum surfaces, inaddition the not-predefined sectional profiles (intermediate profiles)had to be generated from the closest predefined sectional profiles. Ifthese predefined sectional profiles deviated strongly from one another,an automatic interpolation in general led to insufficiently flatsurfaces, resp., to unexpected and undesirable intermediate forms. E.g.,a large circular arc predefined within a sectional profile would notnecessarily be continuously transformed into a smaller predefinedcircular arc in the next sectional profile through circular arcs withreducing radii, but, depending on the interpolation, throughnon-circular intermediate forms. This problem was partially overcome, ifthe user accepted, that between the differing sectional profile typesmanual transition elements (junctions) have to be defined.

[0016] The problem field described above is solved preferably as followsin the case of the invention divulged here: The sectional profiles arein preference described by a single type of geometry, (see FIG. 9),which has to be sufficiently general in nature to be able to describethe common sectional profile forms. Sectional profiles arranged next toeach other are of corresponding nature making sure that no interpolationerrors occur. These sectional profiles are parameterized by formingtechnology scalar values easy to comprehend by the user (hereinafterreferred to as profile parameters), such as, for example componentrun-off length, flange length, flange angle, draw bar height, draw barwidth, draw bar radius, step height, wall angle, die radius, etc. Thesectional profile is then built up based on these profile parameters outof basic elements, for example, circular arcs and line segments, in anautomated manner (in this context refer to FIG. 9). In the case ofinconsistent profile parameters, these are automatically adapted andoptimized in accordance with a defined priority. In this manner, asectional profile can be predefined exceedingly easily and clearly.

[0017] The courses of the intermediate profiles lying between thedefined sectional profiles, in contrast to prior art, are, as a rule notdirectly interpolated. Rather more, first the profile parameters forevery intermediate profile relevant to forming technology areestablished. From these (interpolated) values then the course of theintermediate profiles is built up. This in the case of the examplementioned above leads to the consequence, that the predefined largecircular arc is transformed into the predefined small circular arcthrough exact circular arcs with reducing radii, if the correspondingradius is such a profile parameter.

[0018] In the case of the methods for the creation of addendums knownfrom prior art, height differences and tangent jumps along the edge ofthe component have an effect up to the punch opening line. This ingeneral is undesirable. With the methods known from prior art it istherefore necessary to correct these jumps manually by means oflaborious and time-intensive adaptation of the sectional profiles. Heretoo, an automation is practically impossible.

[0019] In the case of the invention divulged here, this problem issolved as follows. Sectional profiles possess characteristic points,which describe the principal course of the sectional profile. Mentionedas examples for such characteristic points shall be a summit of a drawbar, the flank of a step or the control points of a spline, of aBézier—or of a NURBS curve. Those characteristic points of everysectional profile corresponding to one another can now be joinedtogether and with this form (continuous) characteristic lines, whichextend along an addendum (parallel to a component edge) or at least oversections of it, e.g., the summit line of a draw bar (refer to FIG. 7).The lines defined in this manner are especially suitable for changingthe addendum interactively, in that they, for example, are approximatedas splines easily variable through control points. Both changes in avertical direction (i.e., for example, the course of the height of adraw bar) as well as changes in horizontal direction (i.e., for examplethe horizontal position of the draw bar) can be implemented with this.The change specifically influences the corresponding parameters of thesectional profiles lying in the area of the change and correspondinglythe addendum surface. Since a change of a characteristic line in acontrolled manner influences several adjacent sectional profiles, such achange is significantly easier to implement than by means of the(manual) changing of individual sectional profiles. If the changing of aprofile parameter is to lead to changes of other profile parameters inthe adjacent sections (e.g., the changing of the draw bar height shallsimultaneously cause a change of the width of the draw bar), then acorresponding working connection can be defined by a coupling matrix. Inthe case of the method described here, in addition it is possible toautomatically smooth the characteristic lines. With this, geometry jumpsat the edge of the component can easily be smoothed (in this contextrefer to FIG. 18). As smoothing algorithms, for example, one can againutilize uncoiling algorithms, and this both in the horizontal plane aswell as in the height.

[0020] The concept of the characteristic lines can also be transferredto profile parameters, which cannot be represented as a spatial line onthe addendum, e.g., the run-in radius or a draw bar radius. Such profileparameters are advantageously represented as characteristic lines in anx-y diagram, whereby on the abscissa the path around the addendum and onthe ordinate the profile parameter is applied. The resulting curve can,for example, once again be approximated as a spline easily variablethrough control points. Interactive or automatic changes (e.g.,smoothing) are transformed into a change of the addendum surface inanalogy to the procedure described in the preceding paragraph. Thisprocedure of course is also alternatively applicable to the profileparameters which can be represented as a spatial line.

[0021] If the generated tool geometry is to be checked by means of aforming simulation, or if it is to be automatically optimized in anoptimization loop together with a forming simulation code and a qualitycriterion, then now still lacking is the tying into the formingsimulation. For the forming simulation, as a rule three methods areutilized.

[0022] Single-step-/multi-step simulations based on the componentgeometry. These are usually carried out in accordance with an inverseprocess, whereby the component geometry is departed from, it is squashedflat and the resulting elongations in the flat sheet metal are inprinciple depicted inverted on the component. As a result of theneglecting of the important influence of the addendum and of the binder,such simulations represent a rough estimate. Here they are irrelevant,because the concern here is the assessment of a tool design.

[0023] Single-step-/multi-step simulations based on the tool geometry:Usually carried out in accordance with the same method, here thegeometry of the addendum and of the binder as well as the retainingdevices (e.g., draw beads, binder force) are taken into consideration inthe binder. Required as geometry here is that of the complete tool,therefore in principle the die. The resulting accuracy enables theassessment of a tool design, however, no direct statements about thebehaviour of the sheet metal during the forming can be made. Animportant result of an inverse single step simulation is the requiredoutline of the blank, which is required in order to achieve the outlineof the predefined geometry at the end of the drawing process.Single-step-/multi-step simulations can also be carried out as forwardsmethod, i.e., departing from the blank.

[0024] Incremental simulations based on the tool geometry: Here,departing from the flat blank the forming is simulated in time steps(incrementally). The essential geometrical and process-conditionedinfluencing values can be jointly taken into consideration accurately. Ageometrical description of all participating tools is required,therefore for the simplest forming process a die, a punch and a binder.This method is the most accurate simulation method, calls for, however,significantly more calculation time than a single step process.Available as the result apart from the end condition are also theintermediate conditions.

[0025] For the checking of a tool geometry, the two latter methods arepossible. Current systems for the generation of tools are, however, notvery closely linked to forming simulation systems, so that for theimplementation of simulations in most instances a considerable effortthrough various interfaces and data conversions has to be undertaken.

[0026] The method described above for the creation of addendum zones, inpreference is combinable with a system, in which a parameterizedsimulation model (tool or process) is utilized for the optimization of acomponent. Optionally possible is both a single-step-/multi-step—as wellas an incremental simulation, possibly combined with anevaluation—and/or an optimization module. This system is characterizedas follows:

[0027] Parametric creation of the part tools: From the complete toolsurfaces (component+addendum+binder ring), the utilized tools, e.g., thedie (complete tool surfaces), the punch (tool surfaces without binderring and without die radius) and the binder (binder surface cut-outalong the punch opening line) can be created. An offsetting of thetools, if so required, is automatically carried out. For the creation ofthe punch, if so required, in the wall zone automatically modifiedsectional profiles are utilized (e.g., with a steeper wall angle), inorder to produce the necessary drawing gap. Simultaneously, also theprocess history required for the simulation, i.e., the travel paths ofthe tools, can be generated automatically. A changing of the addendumtherefore automatically entails the corresponding change of the parttools and of their travel paths.

[0028] Parametric creation of the course of the draw beads: Draw beads(beads attached in the binder zone for controlling the sheet metaldraw-in) are automatically generated on the binder surface at apredefined constant or variable distance from the punch opening line orfrom another characteristic line of the addendum. A change of this linethen automatically entails a change of the draw beads.

[0029] Parametric creation of the drawn-in sheet metal outline at theend of the forming for the inverse simulation: For the inversesimulation, in the case of which one predefines the geometry at the endof the forming process, the drawn-in outline of the sheet metal is alsogenerated automatically on the binder surface at a predefined constantor variable distance from the punch opening line or from anothercharacteristic line of the addendum. A changing of this line thenautomatically entails a change of the drawn-in sheet metal outline.

[0030] Parametric creation of the blank outline: The blank outline canbe generated in analogy to the draw bead courses described above. Anadditional variant is described in the following: For an as minimal aspossible consumption of material, the blank should be selected as smallas possible. However, the sheet metal outline during the forming ingeneral should not run into the addendum over the punch opening line,i.e., at the end of the drawing process a small flange should remain inthe binder zone. For this reason, the following procedure is chosenhere: First the drawn-in sheet metal outline for an inverse single-stepsimulation is created as described above. Thereupon the inversesingle-step simulation is carried out. The result of this simulation isthe required blank outline, which is necessary, in order to obtain thepredefined drawn-in sheet metal outline. This procedure is carried outat the beginning of an incremental simulation, in order to find afavourable blank outline for the currently investigated geometryalternative. This procedure makes sense, because the inverse single-stepsimulation requires significantly less calculation time than anincremental simulation. The procedure can be transferred in analogy tothe internal boundaries in case of perforated blanks. In order to savethe tool costs for the trimming tool of the blank, usually a simple,polygonal line blank is preferred, e.g., a rectangular one. If sorequired, the blank outline obtained from the inverse single-stepsimulation is bordered with a rectangle of minimum length and width,whereby the orientation of the rectangle in the horizontal plane ischanged until a rectangle of minimum surface area has been found.Instead of the blank outline obtained from the single-step simulation,this rectangle is now utilized as blank outline for the incrementalsimulation. For other simple polygonal outlines, the procedure isanalogue.

[0031] Every parametric change of the tool surfaces thereforeautomatically results in a changing of the part tools derived from it,of their travel paths, of the draw bead course, of the blank outline,etc., so that the simulation can be restarted again without any manualintervention. In comparison with the prior art, therefore the effort forthe preparation of alternative simulations, whether manual or carriedout automatically within an optimization loop, can be significantlyreduced: When changing the parameters of the tool geometry, immediatelyand fully automatically a new tool geometry and an appertainingconsistent geometry and process model for the simulation are created.

[0032] If desired it is possible to use the geometrical information anddata related to the tool (die, binder, punch) and the sheet metal part,handled and generated by the herein described invention, as input datafor tooling. In this way it is possible to avoid additional processingby a CAD-System which results in a further optimised process.

[0033] The invention is explained in more detail on the basis of thefollowing generalised and simplified figures.

[0034]FIG. 1 shows the essential zones of a forming tool;

[0035]FIG. 2 illustrates a component;

[0036]FIG. 3 shows a course of straight sectional profiles;

[0037]FIG. 4 illustrates a course of curved sectional profiles;

[0038]FIG. 5 shows a design method of initial directions;

[0039]FIG. 6 shows a first addendum with a discontinuous course;

[0040]FIG. 7 illustrates a second addendum with a continuous course;

[0041]FIG. 8 shows a diagram with the essential optimization steps;

[0042]FIG. 9 shows a parameterized sectional profile;

[0043]FIG. 10 illustrates a component with an addendum zone;

[0044]FIG. 11 shows the component in accordance with FIG. 10 withsectional profiles;

[0045]FIG. 12 illustrates a component with optimized sectional profiles;

[0046]FIG. 13 illustrates the interpolation between sectional profiles.

[0047]FIG. 1 illustrates the here essential elements of a forming tool1. Identifiable are a component 2, a component edge 3, an addendum 4, apunch opening line 5 and a binder surface 6.

[0048]FIG. 2 shows a component 2 with an irregular component edge 3. Theirregularities in the course of the edge of the component 3 are filledin with fill surfaces 7 and smoothed. Fill surfaces/making sense, haveto merge C1-continuous (values of the first differentiation identical onboth sides) into the geometry of the component 2. Such surfaces 7 can,for example, be generated through geometrical approximations underC1-boundary condition on the edge of the component 3, or through afinite-element shell solution with C1-boundary condition. The fillsurfaces 7 resulting in this manner are smoothed and continuous andcomplement the component 2 in an optimum manner. In the zone of a fillsurface 7, alternatively an edge 8 of the fill surface 7 is decisive forthe course of the sectional profiles.

[0049]FIG. 3 illustrates the situation, as it is known through priorart. To be seen is a plan view (in direction of the z-axis) of a sectionof a component 2 with a component edge 3 with a concave course. Straightsectional profiles 10, as they are known through prior art, are arrangedvertically to the edge of the component 3. On the basis of thisarrangement, they manifest overlaps.

[0050]FIG. 4 shows a section from the component 2 in accordance withFIG. 3. Identifiable are an addendum 4 and sectional profiles 10. Thesectional profiles here have been created by means of the method inaccordance with the invention. To be identified is the fact, that in theplan view they do not have a straight course, but are curved. Inparticular, they here do not manifest any overlaps. In preference theyare arranged in such a manner, that they correspond to the naturalcourse of geometrical details of the component. E.g., they follow theirextended course in the addendum. With this, the actual edge of thecomponent plays a subordinate role.

[0051]FIG. 5 schematically illustrates how the horizontal initialdirection of a sectional profile 10 is generated. This direction isparticularly advantageously determined by means of the determination ofthe minimum geometry change. Identifiable are a component 2, a componentedge 3 (resp., the edge of a fill surface) and a component edge boundaryzone 22, which is edged by the edge of the component 3 and an innerlimiting line 23. In order to determine the initial direction of asectional profile in a point 25 on the edge of the component 3, resp.,if so required on the edge of fill surfaces (not illustrated in moredetail), a sectional curve 26 between a vertical (parallel to thez-axis) plane 24 also running through the point 25 is formed. Thedeviation of this sectional curve 26 from a straight line 27,represented by a hatched area 28, serves as a measure for the geometrychange. The surface 24 is now varied so long by revolving around avertical axis 30 (illustrated by an arrow 29) running through the point25, until the geometry change fulfils a certain measure. As a rule, thisis a minimum. The initial direction of a sectional profile in ahorizontal plane (x/y-plane), which results from the plane 24, isschematically made clearer by an arrow 31. Another possibility consistsof using the curvature in the edge zone of the component 22 as ameasure. When using the curvature as a measure for the geometry change,the direction of the corresponding sectional profile is advantageouslyplaced in the direction of the smaller principal direction of acurvature tensor projected into a horizontal plane.

[0052]FIG. 6 shows the typical course of characteristic lines 11 in anaddendum 4 of a shape for a component 2. The course of thecharacteristic lines 11 on the basis of great differences in height andtangential jumps is disadvantageously irregular.

[0053]FIG. 7 illustrates a smoothed course of the characteristic lines11 in accordance with FIG. 6. The addendum 4 of the shape for acomponent 2 as a result manifests a significantly more advantageousdesign. Therefore in production much better results are achieved.

[0054]FIG. 8 schematically illustrates the essential steps, which arenecessary for the automatic generation of addendums. The addendum isoptimized by means of a so-called optimizer and a quality criterion.

[0055]FIG. 9 in a generalized manner shows a parameterized cross sectionof a sectional profile 10 as a representative for a single type ofgeometry. The sectional profile 10 is parameterized by means of formingtechnology scalar values (profile parameters), such as, for example,component run-off length, component run-off radius, flange length,flange angle, draw bar height, draw bar width, draw bar radius, stepheight, step radius, wall angle, die radius, etc. The sectional profile10 based on these profile parameters is built up from basic elements,for example circular arcs, splines and line segments, in preference inan automated manner. One or more parametric values may close to or zeroif necessary. Corresponding points are connected to obtain addendumsurfaces.

[0056]FIG. 10 illustrates a geometrical detail 13 and its effect on anaddendum 4. The horizontal directions of the sectional profiles as arule determine, how the geometrical detail 13 of the component 2(feature), which extends to the edge of the component, has an effect onthe addendum 4. It is therefore advantageous, that such geometricaldetails 13 in the component geometry and their branches 14 in theaddendum 4 in essence have the same direction (which is not the case inthis illustration).

[0057]FIG. 11 shows the typical course of sectional profiles 10, whichin accordance with the procedures known from prior art are arrangedvertically to a component edge 3. As a result of this, the result shownin FIG. 10 is produced, in the case of which the branches 14 of ageometrical detail 13 continue in an unfavourable direction in theaddendum 4.

[0058]FIG. 12 now illustrates an arrangement of sectional profiles 10along the edge of the component 3 in accordance with the invention. Thesectional profiles are arranged in such a manner, that the naturalcourse of geometrical details 13 in the component 2 is taken intoaccount. The direction of the branches 14 as a result of this in essencecorresponds to the direction of the geometrical detail 13 in the zone ofthe edge of the component 3

[0059]FIG. 13 is showing in a simplified, idealistic manner a part of anaddendum surface 4 and the arrangement of the sectional profiles 10 inaccordance with FIG. 9. The sectional profiles are parameterised suchthat they are adapted to the geometry. The orientation and the distancebetween sectional profiles is not necessarily equal and is adapted tothe course of the geometry. The sectional profiles are built such thatthey are corresponding to each other. Parametric values may be zero orclose to such that single elements are not visible. The intermediateprofiles are in this example indirectly interpolated: First theparametric values are interpolated, second the at least one profile isregenerated based on these interpolated values and third the surface ofthe addendum is built up based on these sectional profiles and ifavailable intermediate sectional profiles.

1. Method for the creation of addendums (4) of tools for sheet metalformed parts (2) characterized in that initial directions (31) ofsectional profiles (10) are determined, sectional profiles (10) at adistance from one another are arranged along a component (3, 8) withutilization of these initial directions (31) and that an addendum (4) iscreated by connecting the sectional profiles (10).
 2. Method inaccordance with claim 1, characterized in that fill surfaces (7) forsmoothing of an irregular component edge (3) are generated.
 3. Method inaccordance with one of the preceding claims, characterized in that thesectional profiles (10) do not run within a plane.
 4. Method inaccordance with one of the preceding claims, characterized in that thesectional profiles (10) are parameterised and of a single type ofgeometry.
 5. Method in accordance with one of the preceding claims,characterized in that the initial direction (31) of a sectional profileis determined at certain points (25) by minimizing a quality criterion.6. Method in accordance with one of the preceding claims, characterizedin that between the sectional profiles (10) at least one furtherintermediate profile (10) is generated.
 7. Method in accordance withclaim 6, characterized in that the at least one intermediate profile(10) is interpolated indirectly from at least one profile parameter. 8.Method in accordance with one of the preceding claims, characterized inthat characteristic lines (11) are generated by the connection ofcharacteristic points of a sectional profile (10) or as a curve of aparameter value in a diagram.
 9. Method in accordance with claim 8,characterized in that the sectional profiles (10) are changeable withthe utilization of the characteristic lines (11).
 10. Method for thesimulation of the behaviour of tools for sheet metal formed parts (2),characterized in that it contains the process steps in accordance withone of the previous claims.
 11. Method in accordance with claim 10,characterised in that at least one parameter of the simulation iscoupled with the creation of addendums (4) of tools for sheet metalformed parts (2).
 12. Method for the generation of surface data formachining of a tool, characterized in that it contains the process stepsin accordance with one of the previous claims.
 13. Computer programcontaining the steps of the method in accordance with one of theprevious claims.
 14. A computer readable medium containing a program,whereby this program is suitable for making a computer execute the stepsof the method in accordance with claim 1.